CN111590335A

CN111590335A - Smooth pickling production line for controlling transverse fold defects

Info

Publication number: CN111590335A
Application number: CN202010481437.7A
Authority: CN
Inventors: 王野; 齐林雷; 李远旭; 姚广雷; 包红军
Original assignee: Rizhao Baohua New Material Co Ltd
Current assignee: Rizhao Baohua New Material Co Ltd
Priority date: 2020-05-31
Filing date: 2020-05-31
Publication date: 2020-08-28

Abstract

The invention discloses a leveling and pickling production line for controlling a transverse fold line defect, and relates to a metallurgical production line, which comprises an uncoiler, an inlet shear, a welding machine, a leveling machine, an inlet loop, a scale breaker, a pickling section, a rinsing section, a withdrawal and straightening machine, an outlet loop, an outlet shear and a coiling machine which are sequentially connected; the uncoiler is characterized in that the back part of the uncoiler is provided with a reverse bending roller, the reverse bending roller is arranged at the upper back part of a winding drum of the uncoiler, and the wrap angle theta of the reverse bending roller is 35-55 degrees. Compared with the prior art, the production cost can be reduced, and the production efficiency is increased.

Description

Smooth pickling production line for controlling transverse fold defects

Technical Field

The invention relates to a metallurgical production line, in particular to a leveling and pickling production line suitable for controlling the defects of transverse fold lines of steel hot rolling raw materials in iron and steel smelting enterprises.

Background

With the progress of steel rolling technology, hot rolling of thin gauge products is possible. The thickness specification of the hot rolled plate is expanded to 0.7-4.0 mm; the hot rolling raw material coil generates yield in the uncoiling process of an uncoiler of the existing pickling production line, and the surface generates a transverse folding defect vertical to the rolling direction. The thinner the raw material roll thickness specification is, the higher the probability of generating the transverse folding defect is, the more serious the defect degree is, and the outer ring transverse folding defect forms are different, so that the whole roll is wide and short linear shapes are arranged at two sides of the steel roll. Overall, the thin gauge has a 3.5% quality improvement rate due to a cross-fold defect.

The yield platform based on the strip steel is the main reason of the strip steel generating transverse folding, the existing transverse fold defect control method uses a flattening machine to flatten, the inherent yield platform of the strip steel is eliminated, and the plate shape is improved. However, this method has the following problems: firstly, for low-carbon steel hot rolling raw materials with the thin specification of 0.7-1.5mm, the re-leveling effect after acid cleaning is not superposed, the transverse fold line defect cannot be controlled, the cutting amount has to be increased from head to tail, and the strip steel yield is influenced by about 1.2%; waste energy, high production cost and low efficiency.

Disclosure of Invention

The technical task of the invention is to provide an energy-saving and rapid leveling pickling production line for controlling the defects of the transverse wrinkles, aiming at the defects of the prior art.

The technical scheme for solving the technical problem is as follows: the utility model provides a smooth pickling production line of control horizontal fold line defect which characterized in that: the device comprises an uncoiler, an inlet shear, a welding machine, a temper mill, an inlet loop, a scale breaker, an acid washing section, a rinsing section, a tension leveler, an outlet loop, an outlet shear and a coiling machine which are connected in sequence; the uncoiler is characterized in that the back part of the uncoiler is provided with a reverse bending roller, the reverse bending roller is arranged at the upper back part of a winding drum of the uncoiler, and the wrap angle theta of the reverse bending roller is 35-55 degrees.

An oiling machine is also arranged between the outlet loop and the outlet shear.

A first tension roller set is arranged between the welding machine and the leveling machine, a second tension roller set is arranged between the inlet loop and the scale breaker, a third tension roller set is arranged between the scale breaker and the pickling section, and a fourth tension roller set is arranged at two ends of the withdrawal and straightening machine.

The roller diameter of the tension roller group is 1200-1250 mm.

The tension roller is made of tungsten carbide.

Compared with the prior art, the invention has the following outstanding beneficial effects:

1. the strip steel is directly leveled after being welded by a strip steel welding machine, the flatness improves the plate shape and eliminates a yield platform in the strip steel, and then the strip steel is pickled, so that the transverse folding defect caused by yield due to repeated bending of the strip steel in subsequent contact with a roller system can be reduced.

2. And the leveling process after pickling is cancelled, so that the energy is saved.

3. The transportation is not needed, the production cost is reduced, and the production efficiency is increased.

Drawings

Fig. 1 is a schematic structural view of the present invention.

FIG. 2 is a schematic view of the wrap angle of the recurved roll of the present invention.

Detailed Description

The invention is further described with reference to the drawings and the detailed description.

As shown in figure 1, the invention relates to a leveling and pickling production line for controlling a transverse fold defect, which comprises an uncoiler 1, an inlet shear 2, a welding machine 3, a leveling machine 4, an inlet loop 5, a scale breaker 6, a pickling section 7, a rinsing section 8, a withdrawal and straightening machine 9, an outlet loop 10, an outlet shear 12 and a coiler 13 which are connected in sequence.

It is also possible to add an oiling machine 11 between the outlet loop and the outlet shears, depending on the case, and then to carry out the oiling or no-oiling process depending on the case of the final product.

In the optimization scheme, a walking beam feeding device is added before the uncoiler 1.

The technical route is as follows: feeding → uncoiling → shearing → welding → leveling → inlet loop → descaler → acid washing → rinsing → straightening → outlet loop → oiling/not oiling → shearing → coiling.

As shown in fig. 2, the anti-bending roller 14 is arranged at the rear part of the uncoiler, the anti-bending roller 14 is arranged at the upper rear part of the uncoiler drum 15, and the anti-bending roller wrap angle θ is 35-55 °.

When the strip steel is uncoiled, under the action of tension, the hot rolled strip steel 16 with a certain thickness is continuously subjected to the action of bending moment in the process from bending to flattening, the bending moment is continuously increased along with the uncoiling of the strip steel 16, the fiber rate of the surface layer of the strip steel 16 reaches the upper yield strength and is rapidly softened in a local narrow area where the maximum bending moment acts, the fiber rate flows on the stress level of the lower yield strength, and at the moment, if the fiber stress of the surface layer of the strip steel 16 in the adjacent area can exceed the threshold of the upper yield strength, the area where the yield flows is expanded to two sides, and the strip steel 16 is smoothly uncoiled. If the fiber stress on the surface of the strip steel 16 in the adjacent area cannot exceed the threshold of the upper yield strength, the area where the yield flow is limited to the initial part, and the deformed part is bent, namely, the transverse folding defect is generated. The back bending roll 14 arranged at the rear part of the uncoiler enables the strip steel 16 to generate reverse bending deformation, and when the algebraic sum of the internal stress of the strip steel 16 and the stress generated by the back bending roll 14 for bending the strip steel 16 is greater than the upper yield strength and the generated deformation exceeds the yield extension area, the transverse folding can be avoided. Meanwhile, the reverse bending roller 14 presses against the strip steel 16, so that the strip steel 16 can be ensured to be stably deformed layer by layer in the uncoiling process, and transverse folding defects can be caused by nonuniform deformation among layers.

In the prior art, the control of the reverse bending roll comprises two modes:

position control: the pressing position of the reverse bending roller is adjusted along with the diameter change in the uncoiling process. According to the relative relation between the outer diameter of the steel coil and the extension of the hydraulic cylinder, the anti-bending roller automatically adjusts the extension position according to the coil diameter.

Pressure control: and (3) according to the pressure generated by the hydraulic cylinder on the strip steel, keeping the pressure of the hydraulic cylinder at a set value, and automatically adjusting the position of the reverse bending roller.

However, in practice, in the case of thin gauge strip steel, the hot rolled coil tends to yield more at the head and tail than at the middle during uncoiling, and therefore, neither constant position control nor constant pressure can be improved.

The present invention therefore proposes a wrap angle control concept. As shown in FIG. 2, the wrap angle θ is an angle formed by a median line of the arc surface of the contact portion of the reverse bending roll 14 and the strip steel 16 and a tangent line of the strip steel 15 and the strip steel 16. The wrap angle is constant, the strip steel can be uniformly deformed in the process of pressing down the reverse bending roll, and the probability of generating transverse folding defects is reduced. When the position of the anti-bending roller is set to have a wrap angle of 35-55 degrees, the transverse fold defects can be reduced.

The low-carbon steel has different thickness specifications, and the control angle of the reverse bending roll has corresponding optimized values, as shown in the following table:

thickness (mm)	Wrap angle
		0.7～1.2mm	45～46゜
1.2～1.5mm	44～45゜
		＞1.5mm	40～43゜

The specific control method of the angle of the reverse bending roller can be various, and a person skilled in the art can set the extending position by using the variables of the specific model of the uncoiler, the diameter specification and the thickness specification of the steel coil.

The back-bending roller in the production line is seriously worn, the strip steel pressed in the uncoiling process is very unstable, the transverse fold line defect is easily generated, and particularly, the thin strip steel often has the plate shape defect and is more easily transversely folded. The production line reverse bending roll is made of tungsten carbide, and is high in hardness and good in wear resistance. Meanwhile, the use period is shortened from 5 months to 2 months.

The leveling in the traditional process aims at leveling the surface after scale breaking and acid pickling, and the yield is not obviously improved.

After the strip steel is reversely bent and deformed by the reverse bending roller 14 of the uncoiler, the stable deformation can be attenuated along with the forward process of a production line, the thickness of the traditional strip steel is thicker, so that the deformation attenuation cannot cause excessive transverse folding, the subsequent flattening and straightening processes can be effectively corrected, but for low-carbon steel hot rolling raw materials with the thin specification of 0.7-1.5mm, the attenuation of the deformation is more obvious, and the low-carbon steel hot rolling raw materials are easy to yield in the repeated bending process of a roller system to generate transverse folding lines, so that the later correction failure is caused. Therefore, the invention places the temper mill behind the welding machine, adds the temper mill at the position, and can keep the benign uniform deformation effect caused by reverse bending under the matching of the wrap angle theta of the reverse bending roller, eliminate the inherent yield platform of the strip steel, and match the tension of the tension roller, reduce the subsequent working procedures of the hot-rolled strip steel coil, and the strip steel is repeatedly bent when passing through the roller system to have the transverse bending defect, so that the effect is stable and continuous without secondary temper rolling.

The working principle of the tension roller is as follows: the strip steel is wound on the tension roller, and friction force is generated at the winding contact part (namely a winding angle) of the strip steel, so that tension difference is generated between the outlet and the inlet, the tension value of the strip steel at the inlet or the outlet of the tension roller is changed, and tension control is realized on the unit. The roll diameter of a tension roll of the pickling production line influences the transverse folding of thin-specification strip steel, the roll diameter of the tension roll is small, the curvature is large, the strip steel is easy to yield in the process of winding the tension roll, the transverse folding is particularly obvious for the strip steel with the thickness less than or equal to 1.0mm, and the probability of transverse folding is higher.

A first tension roller set is arranged between the welding machine 3 and the leveling machine 4, a second tension roller set is arranged between the inlet loop 5 and the descaling machine 6, a third tension roller set is arranged between the pickling section 7 and the descaling machine 6, and a fourth tension roller set is arranged at two ends of the withdrawal and straightening machine 9. The roller diameter of the tension roller group is controlled to be 1200-1250 mm.

And the roller surface abrasion of the tension roller needs to be less than 2.0 mm. That is, the roller surface of the tension roller is abraded by ≧ 2.0mm, and the roller surface must be replaced.

When the production line is used for production, the above steps are specifically controlled as described below, and the parts not mentioned are consistent with the prior art, so the description is not repeated.

1. Feeding process

(1) Controlling the feeding temperature of the raw material roll

The feeding temperature of the raw material roll is controlled to be less than or equal to 45 DEG C

(2) Controlling storage time in stock repository

Compared with the prior art, the storage time of the thin-specification low-carbon steel in the raw material warehouse is prolonged. The metal or alloy is kept for a period of time at a certain temperature, the strength is gradually increased, and the elongation is gradually reduced. The invention utilizes the effect of the aging of the strip steel, prolongs the feeding time of the strip steel, considers the strength and the elongation rate in two ways, reasonably improves the yield strength of the raw materials and reduces the probability of generating transverse wrinkles. Specifically, the strip steel with the thickness of 0.7-1.2mm needs to be stored for more than 5 days, and the strip steel with the thickness of 1.2-1.5mm needs to be stored for more than 4 days.

And the online production can be realized only if the temperature and the storage time of the raw material roll meet the requirements.

The feeding can be realized by adopting a walking beam.

2. Uncoiling process

On the basis of the wrap angle control of the reverse bending roll, the combination of increasing the uncoiling tension and the uncoiling speed of the hot-rolled coil can ensure uniform deformation so as to reduce the probability of generating transverse fold line defects.

The uncoiling maximum speed designed by the production line is 800 m/min; the uncoiling tension is designed to be 30 KN.

The actual uncoiling speed is set according to the thickness specification: for low-carbon steel with the thickness of more than or equal to 0.7mm and less than or equal to 1.2mm, the uncoiling speed must be kept above 700m/min in the uncoiling process; for low-carbon steel with the thickness of more than 1.2mm and less than or equal to 1.5mm, the uncoiling speed must be kept above 600m/min in the uncoiling process;

as shown in the table below, the uncoiling tension range is selected according to the width and thickness specifications, and strip steel with the thickness not more than 1.5mm under the condition allowed by the conditions in the production process is uncoiled by adopting the maximum tension.

3. Scale breaking procedure

When the working roll of the scale breaker is seriously worn, the seriously worn position of the working roll of the scale breaker can be unevenly deformed when the strip steel is bent by the scale breaker, and the worn shape of the scale breaker can generate a transverse folding defect on the surface of the strip steel. The transverse folding defect generated by the scale breaker is characterized in that the transverse position of the strip steel is fixed and corresponds to the abrasion position of a working roll of the scale breaker, and the full length of the whole roll of the strip steel exists.

In order to reduce the probability of the cross-folding of the working roller of the scale breaker, the working roller of the scale breaker is made of tungsten carbide, so that the wear resistance of the working roller of the scale breaker can be improved, and the period is prolonged.

Setting the grinding period of the working roller: usually, the working period of the ordinary descaler is 1100-1400km, and the working roller period of the descaler made of tungsten carbide is 6000-6500 km.

In the optimization scheme, the following control modes can be added

(1) Reducing the stagger degree of the scale breaker

The stagger degree of all thickness specifications in traditional production is in the range of 50-55 mm. The stagger degree of the scale breaker is reduced to 20-40mm, so that the deformation curvature of the strip steel is reduced, the tension of the scale breaker is increased, and the elongation of the scale breaker is ensured to be unchanged.

(2) Elongation setting of scale breaker

The elongation percentage range of the scale breaker in the traditional production is 0.8-1.2%, the elongation percentage of the scale breaker can be reduced to 0.4-0.6%, the reduced elongation percentage is increased to the elongation percentage of a temper mill, and the total elongation percentage of the strip steel is ensured to be unchanged.

The following are the various control parameters of the specific embodiment: the parameters not mentioned in the table are according to the parameter ranges and methods described in the above control modes.

In addition, in order to compare the technical effects of the prior art and the present invention, three control groups were also set:

in comparison group 1, the process is a conventional process, namely: feeding → uncoiling → shearing → welding → inlet loop → descaler → acid washing → rinsing → leveling → straightening → outlet loop → oiling/not oiling → shearing → coiling. The uncoiler reverse bending roller is controlled by adopting position control, the relative relation between the external diameter of the steel coil and the extension of the hydraulic cylinder is-0.2952 x +1276.2, and the extension position of the reverse bending roller is automatically adjusted according to the size of the coil diameter. The remaining parameters were the same as in example 1.

In comparison group 2, the process was a conventional process, the parameters of example 1 were used for setting, the reverse bending roll was wrap angle controlled, and the wrap angle degree was 45 °.

Control 3 was set in the procedure of example 1, but the position control in control 1 was used for the uncoiler reverse bending control. The remaining parameters were the same as in example 1.

The results show that the judgment rate of the transverse fold lines of each example is less than 0.5 percent, and the judgment rates of the control groups are respectively as follows: 3.5%, 2.4%, 1.8%, which are significantly different from the group of example 1.

It should be noted that while the invention has been described in detail with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various obvious changes can be made therein without departing from the spirit and scope of the invention.

Claims

1. The utility model provides a smooth pickling production line of control horizontal fold line defect which characterized in that: the device comprises an uncoiler, an inlet shear, a welding machine, a temper mill, an inlet loop, a scale breaker, an acid washing section, a rinsing section, a tension leveler, an outlet loop, an outlet shear and a coiling machine which are connected in sequence; the uncoiler is characterized in that the back part of the uncoiler is provided with a reverse bending roller, the reverse bending roller is arranged at the upper back part of a winding drum of the uncoiler, and the wrap angle theta of the reverse bending roller is 35-55 degrees.

2. The flatting acid production line for controlling the defects of the transverse wrinkles as claimed in claim 1, wherein: an oiling machine is also arranged between the outlet loop and the outlet shear.

3. The flatting acid production line for controlling the defects of the transverse wrinkles as claimed in claim 1, wherein: a first tension roller set is arranged between the welding machine and the leveling machine, a second tension roller set is arranged between the inlet loop and the scale breaker, a third tension roller set is arranged between the scale breaker and the pickling section, and a fourth tension roller set is arranged at two ends of the withdrawal and straightening machine.

4. The flatting acid production line for controlling the defects of the transverse wrinkles as claimed in claim 3, wherein: the roller diameter of the tension roller group is 1200-1250 mm.

5. The flatting acid production line for controlling the defects of the transverse wrinkles as claimed in claim 3, wherein: the tension roller is made of tungsten carbide.